Improve spinloop detection #786
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FYI, this is a small precursor of #772. |
dartagnan/src/main/java/com/dat3m/dartagnan/program/processing/DynamicSpinLoopDetection.java
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Updated verdict of VMMLocksTest
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* Improve DynamicSpinLoopDetection * Update verdict of VMMLocksTest
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Using the new tuple support from #775, this PR improves the detection of local side effects in loops.
Rather than treating any assignment to live variables as a side-effect, we now check that the register's values have actually changed. In other words, the check is more semantic now.
This PR also fixes a bug where we failed to detect certain side-effects in cases where the loop only writes to but does not read from a register (only happened in Libvsync benchmarks AFAIK).
I know of at least one verdict that has changed (
clh_mutex) but I haven't updated the unit tests yet.After the CI runs through, I will update the unit tests with the new expectation.
EDIT: Only in the VMM tests we get a different verdict for
clh_mutex. This confused me at the beginning, but the reason is that we unroll the code twice whereas we do only once in all other lock benchmarks (for C11, TSO, ARM, and POWER).